I. Field of the Invention
The present invention relates generally to enteral feeding tube assemblies having a stylet wire for guiding the tube into the stomach and more specifically to an improved retaining means for retaining the stylet wire within the tube while providing a larger orifice.
II. Prior Art
Enteral feeding tubes or naso-gastric tubes are well known in the art. Such devices have long been used in feeding compromised patients who are unable to take food orally. The tube provides access through the nasal passage into the stomach or duodenum for the direct administration of liquid nutrition and medication.
The tube generally comprises a weighted distal end for retaining the tube in position in the stomach, a hollow bolus having a distal orifice through which the nutrition is administered, and a tube which extends up through the esophagus through the nasal nasopharynx or oropharynx. The tube is inserted through the nasopharynx and the esophagus with the aid of a stylet guide wire. The stylet wire is placed within the tube up to the distal orifice to provide required rigidity to assist in the insertion of the tube into the stomach.
Most current enteral feeding tubes need such a semi-rigid stylet wire to stiffen the tube enough to permit intubation. The stiff wire poses a serious danger if it is allowed to protrude from the feeding tube, for instance through the hole or holes which comprise the distal orifice. Therefore, in current feeding tubes, these holes are often kept much smaller than the tube inner diameter (and thus smaller than the wire tip). This in turn creates flow difficulties that can lead to tube clogging. Also, smaller holes can more easily be blocked as the tube lies against the stomach wall.
Another attempted solution has been to provide a rigid molded piece with right-angle holes to discourage the protrusion of the stylet wire. Such an interruption in the flow path can result in clogging. Also, the length of the wire will be calculated such that the wire tip should locate within the rigid molded piece entrance section proximal of the holes. However, manufacturing tolerances and/or tube compression during use dictate that the wire tip may end up in (or through) the exit holes within the rigid molded piece. Also, in designing the holes in such a manner as to discourage protrusion of the stylet wire, the holes are down-sized with the result of lower flow capabilities.
An example of a rigid molded piece within an enteral feeding tube of the type described can be found in U.S. Pat. No. 4,490,143. This type of device is an improvement over the prior art design of providing perforations through the wall of the flexible tube itself. However, there can still be clogging problems within the right angle of the flow path and protrusion of the stylet wire is still possible.